The present invention relates to a spring mattress comprising springs enclosed in casings, a so-called pocket spring mattress, as well as a method and a device for manufacturing such a mattress.
A common technique of making spring mattresses is the so-called pocket technique. This means that the springs are enclosed in pockets, i.e. they are individually enclosed by a casing material. In this way, the springs will be relatively individually resilient so that they can flex individually without affecting the neighbouring springs and, thus, the comfort to the user increases since his weight will thus be distributed more uniformly over the surface that receives the load.
A drawback of such mattresses is, however, that it is difficult to make thin mattresses. If the length of the springs is reduced without a corresponding reduction of the width, the spring will, especially when the length approaches the length of the diameter of the spring, have a tendency to turn in the casing, which dramatically deteriorates the comfort of the mattress. When such mattresses are to be manufactured, the existing technique requires a much larger number of springs. Consequently the manufacture will be considerably more expensive and more complicated. Besides it is difficult to prevent such mattresses from also being stiffer since too thin spring wire cannot be used.
For these reasons, it has not been possible to use spring mattresses for many purposes where thinner mattresses are required, such as for bed mattresses, seat cushions and the like. In spite of this, spring mattresses have several properties making it desirable to use them also in these contexts, such as excellent comfort, individual flexibility, a long life and easy and inexpensive manufacture.
It is therefore an object of the present invention to provide a spring mattress of the type mentioned by way of introduction, as well as a method and a device for manufacturing the same, in which the above drawbacks are obviated wholly or at least partly.
This object is achieved by a spring mattress and a method for manufacturing the same according to the appended claims.